1. Technical Field
This invention relates to a test transmitter for a cellular mobile radio network as set forth in the preamble of claim 1 and to a method and a computer for testing a cellular mobile radio network as set forth in the preambles of the respective independent claims.
2. Discussion of Related Art
From a product information sheet of Motorola, Swindon, United Kingdom, entitled "Digital Cellular Traffic Hotspot Detector", a test transmitter ("beacon") for a cellular mobile radio network, namely for the network based on the GSM standard (GSM: Global System for Mobile Communications), is known. This test transmitter continuously transmits a "dummy BCCH" signal, i.e., a test signal for reception by mobile stations which are located in the coverage area of the mobile radio network. In the computer-aided "hotspot detection" process described there, the test transmitter is established at a test location in the coverage area of the mobile radio network; then, a test signal is transmitted by the test transmitter and received by the mobile stations located in the coverage area of the mobile radio network. Each of the mobile stations which receives the test signal measures the receive level of this signal and reports it to the base station currently serving the cell. A computer connected to this base station analyzes the receive levels reported by several mobile stations in order to determine whether the test location is suitable for installing a base station. The test location is considered suitable if the majority of mobile stations identifies the test signal as being stronger than the broadcast signal being transmitted by the serving base station. The test signal is not present on the so-called neighbor list of the cellular radio network, so that the mobile stations will not identify the test signal as a broadcast signal typical of the mobile radio network and will not attempt to hand over to the test transmitter. Accordingly, the test signal is transmitted arbitrarily on an unassigned carrier. To be able to receive the test signal on this carrier, however, a mobile station must know this carrier and lock its receiver onto this carrier.